1
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Ross TW, Poulter SL, Lever C, Easton A. Mice integrate conspecific and contextual information in forming social episodic-like memories under spontaneous recognition task conditions. Sci Rep 2024; 14:16159. [PMID: 38997341 PMCID: PMC11245605 DOI: 10.1038/s41598-024-66403-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 07/01/2024] [Indexed: 07/14/2024] Open
Abstract
The ability to remember unique past events (episodic memory) may be an evolutionarily conserved function, with accumulating evidence of episodic-(like) memory processing in rodents. In humans, it likely contributes to successful complex social networking. Rodents, arguably the most used laboratory models, are also rather social animals. However, many behavioural paradigms are devoid of sociality, and commonly-used social spontaneous recognition tasks (SRTs) are open to non-episodic strategies based upon familiarity. We address this gap by developing new SRT variants. Here, in object-in-context SRTs, we asked if context could be specified by the presence/absence of either a conspecific (experiment 1) or an additional local object (experiment 2). We show that mice readily used the conspecific as contextual information to distinguish unique episodes in memory. In contrast, no coherent behavioural response emerged when an additional object was used as a potential context specifier. Further, in a new social conspecific-in-context SRT (experiment 3) where environment-based change was the context specifier, mice preferably explored a more recently-seen familiar conspecific associated with contextual mismatch, over a less recently-seen familiar conspecific presented in the same context. The results argue that, in incidental SRT conditions, mice readily incorporate conspecific cue information into episodic-like memory. Thus, the tasks offer different ways to assess and further understand the mechanisms at work in social episodic-like memory processing.
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Affiliation(s)
- T W Ross
- Department of Psychology, Durham University, South Road, Durham, DH1 3LE, UK.
- Centre for Learning and Memory Processes, Durham University, Durham, UK.
| | - S L Poulter
- Department of Psychology, Durham University, South Road, Durham, DH1 3LE, UK
- Centre for Learning and Memory Processes, Durham University, Durham, UK
| | - C Lever
- Department of Psychology, Durham University, South Road, Durham, DH1 3LE, UK
- Centre for Learning and Memory Processes, Durham University, Durham, UK
| | - A Easton
- Department of Psychology, Durham University, South Road, Durham, DH1 3LE, UK
- Centre for Learning and Memory Processes, Durham University, Durham, UK
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2
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Jeffery KJ. The mosaic structure of the mammalian cognitive map. Learn Behav 2024; 52:19-34. [PMID: 38231426 PMCID: PMC10923978 DOI: 10.3758/s13420-023-00618-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/27/2023] [Indexed: 01/18/2024]
Abstract
The cognitive map, proposed by Tolman in the 1940s, is a hypothetical internal representation of space constructed by the brain to enable an animal to undertake flexible spatial behaviors such as navigation. The subsequent discovery of place cells in the hippocampus of rats suggested that such a map-like representation does exist, and also provided a tool with which to explore its properties. Single-neuron studies in rodents conducted in small singular spaces have suggested that the map is founded on a metric framework, preserving distances and directions in an abstract representational format. An open question is whether this metric structure pertains over extended, often complexly structured real-world space. The data reviewed here suggest that this is not the case. The emerging picture is that instead of being a single, unified construct, the map is a mosaic of fragments that are heterogeneous, variably metric, multiply scaled, and sometimes laid on top of each other. Important organizing factors within and between fragments include boundaries, context, compass direction, and gravity. The map functions not to provide a comprehensive and precise rendering of the environment but rather to support adaptive behavior, tailored to the species and situation.
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Affiliation(s)
- Kate J Jeffery
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
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3
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Shan X, Contreras MP, Sawangjit A, Dimitrov S, Born J, Inostroza M. Rearing is critical for forming spatial representations in pre-weanling rats. Behav Brain Res 2023; 452:114545. [PMID: 37321311 DOI: 10.1016/j.bbr.2023.114545] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 05/24/2023] [Accepted: 06/13/2023] [Indexed: 06/17/2023]
Abstract
Rearing, i.e., standing on the hind limbs in an upright posture, is part of a rat's innate exploratory motor program. Here, we examined in developing rats whether rearing is critical for the pup's capability to form spatial representations based on distal environmental cues. Pups (male) were tested at PD18, i.e., the first day they typically exhibit stable rearing, on a spatial habituation paradigm comprising a Familiarization session (with the pup exposed to an arena with a specific configuration of distal cues) followed, 3 h later, by a Test session where the pups were either re-exposed to the identical distal cue configuration (NoChange) or a changed configuration (DistalChange). In Experiment 1, rearing activity (rearing events, duration) decreased from Familiarization to Test in the NoChange pups but, remained elevated in the DistalChange group indicating that these pups recognized the distal novelty. Recognition of distal novelty was associated with increased c-Fos expression in hippocampal and medial prefrontal cortex (mPFC) areas, compared with NoChange pups. Analysis of GAD67+ cells suggested a parallel increase in excitation and inhibition specifically in prelimbic mPFC networks in response to distal cue changes. In Experiment 2, the pups were mechanically prevented from rearing while still seeing the distal cues during Familiarization. Rearing activity in the Test session of these pups did not differ between groups that were or were not exposed to a changed distal cue configuration at Test. The findings evidence a critical role of rearing for the emergence of allocentric representations integrating distal space during early development.
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Affiliation(s)
- Xia Shan
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany; Graduate School of Neural & Behavioural Science, International Max Planck Research School, Tübingen, Germany
| | - María Paz Contreras
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany; Graduate School of Neural & Behavioural Science, International Max Planck Research School, Tübingen, Germany
| | - Anuck Sawangjit
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany
| | - Stoyan Dimitrov
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany
| | - Jan Born
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany; German Center for Diabetes Research (DZD), Institute for Diabetes Research & Metabolic Diseases of the Helmholtz Center Munich at the University Tübingen (IDM), Germany; Werner Reichert Center for Integrative Neuroscience, University of Tübingen, Tübingen, Germany; German Center for Mental Health (DZPG), Germany.
| | - Marion Inostroza
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany.
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4
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Layfield D, Sidell N, Blankenberger K, Newman EL. Hippocampal inactivation during rearing on hind legs impairs spatial memory. Sci Rep 2023; 13:6136. [PMID: 37061540 PMCID: PMC10105745 DOI: 10.1038/s41598-023-33209-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 04/09/2023] [Indexed: 04/17/2023] Open
Abstract
Spatial memory requires an intact hippocampus. Hippocampal function during epochs of locomotion and quiet rest (e.g., grooming and reward consumption) has been the target of extensive study. However, during navigation rats frequently rear up onto their hind legs, and the importance of hippocampal activity during these periods of attentive sampling for spatial memory is unknown. To address this, we tested the necessity of dorsal hippocampal activity during rearing epochs in the study phase of a delayed win-shift task for memory performance in the subsequent test phase. Hippocampal activity was manipulated with closed-loop, bilateral, optogenetic inactivation. Spatial memory accuracy was significantly and selectively reduced when the dorsal hippocampus was inactivated during rearing epochs at encoding. These data show that hippocampal activity during periods of rearing can be important for spatial memory, revealing a novel link between hippocampal function during epochs of rearing and spatial memory.
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Affiliation(s)
- Dylan Layfield
- Program in Neuroscience, Indiana University, 1101 E 10th St, Bloomington, IN, 47405, USA.
- Department of Psychological and Brain Sciences, Indiana University, 1101 E 10th St, Bloomington, IN, 47405, USA.
| | - Nathan Sidell
- Department of Psychological and Brain Sciences, Indiana University, 1101 E 10th St, Bloomington, IN, 47405, USA
| | - Kevin Blankenberger
- Department of Psychological and Brain Sciences, Indiana University, 1101 E 10th St, Bloomington, IN, 47405, USA
| | - Ehren Lee Newman
- Program in Neuroscience, Indiana University, 1101 E 10th St, Bloomington, IN, 47405, USA
- Department of Psychological and Brain Sciences, Indiana University, 1101 E 10th St, Bloomington, IN, 47405, USA
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5
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Two distinct ways to form long-term object recognition memory during sleep and wakefulness. Proc Natl Acad Sci U S A 2022; 119:e2203165119. [PMID: 35969775 PMCID: PMC9407643 DOI: 10.1073/pnas.2203165119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Memory consolidation is promoted by sleep. However, there is also evidence for consolidation into long-term memory during wakefulness via processes that preferentially affect nonhippocampal representations. We compared, in rats, the effects of 2-h postencoding periods of sleep and wakefulness on the formation of long-term memory for objects and their associated environmental contexts. We employed a novel-object recognition (NOR) task, using object exploration and exploratory rearing as behavioral indicators of these memories. Remote recall testing (after 1 wk) confirmed significant long-term NOR memory under both conditions, with NOR memory after sleep predicted by the occurrence of EEG spindle-slow oscillation coupling. Rats in the sleep group decreased their exploratory rearing at recall testing, revealing successful recall of the environmental context. By contrast, rats that stayed awake after encoding showed equally high levels of rearing upon remote testing as during encoding, indicating that context memory was lost. Disruption of hippocampal function during the postencoding interval (by muscimol administration) suppressed long-term NOR memory together with context memory formation when animals slept, but enhanced NOR memory when they were awake during this interval. Testing remote recall in a context different from that during encoding impaired NOR memory in the sleep condition, while exploratory rearing was increased. By contrast, NOR memory in the wake rats was preserved and actually superior to that after sleep. Our findings indicate two distinct modes of long-term memory formation: Sleep consolidation is hippocampus dependent and implicates event-context binding, whereas wake consolidation is impaired by hippocampal activation and strengthens context-independent representations.
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6
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Kayyal H, Chandran SK, Yiannakas A, Gould N, Khamaisy M, Rosenblum K. Insula to mPFC reciprocal connectivity differentially underlies novel taste neophobic response and learning in mice. eLife 2021; 10:66686. [PMID: 34219650 PMCID: PMC8282338 DOI: 10.7554/elife.66686] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 06/29/2021] [Indexed: 12/18/2022] Open
Abstract
To survive in an ever-changing environment, animals must detect and learn salient information. The anterior insular cortex (aIC) and medial prefrontal cortex (mPFC) are heavily implicated in salience and novelty processing, and specifically, the processing of taste sensory information. Here, we examined the role of aIC-mPFC reciprocal connectivity in novel taste neophobia and memory formation, in mice. Using pERK and neuronal intrinsic properties as markers for neuronal activation, and retrograde AAV (rAAV) constructs for connectivity, we demonstrate a correlation between aIC-mPFC activity and novel taste experience. Furthermore, by expressing inhibitory chemogenetic receptors in these projections, we show that aIC-to-mPFC activity is necessary for both taste neophobia and its attenuation. However, activity within mPFC-to-aIC projections is essential only for the neophobic reaction but not for the learning process. These results provide an insight into the cortical circuitry needed to detect, react to- and learn salient stimuli, a process critically involved in psychiatric disorders.
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Affiliation(s)
- Haneen Kayyal
- Sagol Department of Neuroscience, University of Haifa, Mount Carmel, Israel
| | | | - Adonis Yiannakas
- Sagol Department of Neuroscience, University of Haifa, Mount Carmel, Israel
| | - Nathaniel Gould
- Sagol Department of Neuroscience, University of Haifa, Mount Carmel, Israel
| | - Mohammad Khamaisy
- Sagol Department of Neuroscience, University of Haifa, Mount Carmel, Israel
| | - Kobi Rosenblum
- Sagol Department of Neuroscience, University of Haifa, Mount Carmel, Israel.,Center for Gene Manipulation in the Brain, University of Haifa, Mount Carmel, Israel
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7
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Abstract
There are currently a number of theories of rodent hippocampal function. They fall into two major groups that differ in the role they impute to space in hippocampal information processing. On one hand, the cognitive map theory sees space as crucial and central, with other types of nonspatial information embedded in a primary spatial framework. On the other hand, most other theories see the function of the hippocampal formation as broader, treating all types of information as equivalent and concentrating on the processes carried out irrespective of the specific material being represented, stored, and manipulated. One crucial difference, therefore, is the extent to which theories see hippocampal pyramidal cells as representing nonspatial information independently of a spatial framework. Studies have reported the existence of single hippocampal unit responses to nonspatial stimuli, both to simple sensory inputs as well as to more complex stimuli such as objects, conspecifics, rewards, and time, and these findings been interpreted as evidence in favor of a broader hippocampal function. Alternatively, these nonspatial responses might actually be feature-in-place signals where the spatial nature of the response has been masked by the fact that the objects or features were only presented in one location or one spatial context. In this article, we argue that when tested in multiple locations, the hippocampal response to nonspatial stimuli is almost invariably dependent on the animal's location. Looked at collectively, the data provide strong support for the cognitive map theory.
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Affiliation(s)
- John O'Keefe
- Sainsbury Wellcome Centre and Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Julija Krupic
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
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8
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Ben-Yishay E, Krivoruchko K, Ron S, Ulanovsky N, Derdikman D, Gutfreund Y. Directional tuning in the hippocampal formation of birds. Curr Biol 2021; 31:2592-2602.e4. [PMID: 33974847 DOI: 10.1016/j.cub.2021.04.029] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 04/02/2021] [Accepted: 04/12/2021] [Indexed: 11/18/2022]
Abstract
Birds strongly rely on spatial memory and navigation. Therefore, it is of utmost interest to reveal how space is represented in the avian brain. Here we used tetrodes to record neurons from the hippocampal formation of Japanese quails-a ground-dwelling species-while the quails roamed in an open-field arena. Whereas spatially modulated cells (place cells, grid cells, border cells) were generally not encountered, the firing rate of about 12% of the neurons was unimodally and significantly modulated by the head azimuth-i.e., these were head-direction cells (HD cells). Typically, HD cells were maximally active at one preferred direction and minimally at the opposite null direction, with preferred directions spanning all 360° across the population. The preferred direction was independent of the animal's position and speed and was stable during the recording session. The HD tuning was broader compared to that of HD cells in rodents, and most cells had non-zero baseline firing in all directions. However, similar to findings in rodents, the HD tuning usually rotated with the rotation of a salient visual cue in the arena. Thus, these findings support the existence of an allocentric HD representation in the quail hippocampal formation and provide the first demonstration of HD cells in birds.
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Affiliation(s)
- Elhanan Ben-Yishay
- Department of Neurobiology, Rappaport Research Institute and Faculty of Medicine, Technion - Israel Institute of Technology, 1 Efron Street, Haifa 3525422, Israel
| | - Ksenia Krivoruchko
- Department of Neurobiology, Rappaport Research Institute and Faculty of Medicine, Technion - Israel Institute of Technology, 1 Efron Street, Haifa 3525422, Israel
| | - Shaked Ron
- Department of Neurobiology, Rappaport Research Institute and Faculty of Medicine, Technion - Israel Institute of Technology, 1 Efron Street, Haifa 3525422, Israel
| | - Nachum Ulanovsky
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Dori Derdikman
- Department of Neurobiology, Rappaport Research Institute and Faculty of Medicine, Technion - Israel Institute of Technology, 1 Efron Street, Haifa 3525422, Israel
| | - Yoram Gutfreund
- Department of Neurobiology, Rappaport Research Institute and Faculty of Medicine, Technion - Israel Institute of Technology, 1 Efron Street, Haifa 3525422, Israel.
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9
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Duvelle É, Grieves RM, Hok V, Poucet B, Arleo A, Jeffery KJ, Save E. Insensitivity of Place Cells to the Value of Spatial Goals in a Two-Choice Flexible Navigation Task. J Neurosci 2019; 39:2522-2541. [PMID: 30696727 PMCID: PMC6435828 DOI: 10.1523/jneurosci.1578-18.2018] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 12/19/2018] [Accepted: 12/21/2018] [Indexed: 01/28/2023] Open
Abstract
Hippocampal place cells show position-specific activity thought to reflect a self-localization signal. Several reports also point to some form of goal encoding by place cells. We investigated this by asking whether they also encode the value of spatial goals, which is crucial information for optimizing goal-directed navigation. We used a continuous place navigation task in which male rats navigate to one of two (freely chosen) unmarked locations and wait, triggering the release of reward, which is then located and consumed elsewhere. This allows sampling of place fields and dissociates spatial goal from reward consumption. The two goals varied in the amount of reward provided, allowing assessment of whether the rats factored goal value into their navigational choice and of possible neural correlates of this value. Rats successfully learned the task, indicating goal localization, and they preferred higher-value goals, indicating processing of goal value. Replicating previous findings, there was goal-related activity in the out-of-field firing of CA1 place cells, with a ramping-up of firing rate during the waiting period, but no general overrepresentation of goals by place fields, an observation that we extended to CA3 place cells. Importantly, place cells were not modulated by goal value. This suggests that dorsal hippocampal place cells encode space independently of its associated value despite the effect of that value on spatial behavior. Our findings are consistent with a model of place cells in which they provide a spontaneously constructed value-free spatial representation rather than encoding other navigationally relevant but nonspatial information.SIGNIFICANCE STATEMENT We investigated whether hippocampal place cells, which compute a self-localization signal, also encode the relative value of places, which is essential information for optimal navigation. When choosing between two spatial goals of different value, rats preferred the higher-value goal. We saw out-of-field goal firing in place cells, replicating previous observations that the cells are influenced by the goal, but their activity was not modulated by the value of these goals. Our results suggest that place cells do not encode all of the navigationally relevant aspects of a place, but instead form a value-free "map" that links to such aspects in other parts of the brain.
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Affiliation(s)
- Éléonore Duvelle
- Aix Marseille University, Centre National de la Recherche Scientifique (CNRS), Laboratory of Cognitive Neuroscience, Marseille, France
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France, and
- Institute of Behavioural Neuroscience, Division of Psychology and Language Sciences, University College London, London WC1H 0AP, United Kingdom
| | - Roddy M Grieves
- Institute of Behavioural Neuroscience, Division of Psychology and Language Sciences, University College London, London WC1H 0AP, United Kingdom
| | - Vincent Hok
- Aix Marseille University, Centre National de la Recherche Scientifique (CNRS), Laboratory of Cognitive Neuroscience, Marseille, France
| | - Bruno Poucet
- Aix Marseille University, Centre National de la Recherche Scientifique (CNRS), Laboratory of Cognitive Neuroscience, Marseille, France
| | - Angelo Arleo
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France, and
| | - Kate J Jeffery
- Institute of Behavioural Neuroscience, Division of Psychology and Language Sciences, University College London, London WC1H 0AP, United Kingdom
| | - Etienne Save
- Aix Marseille University, Centre National de la Recherche Scientifique (CNRS), Laboratory of Cognitive Neuroscience, Marseille, France,
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10
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Abstract
Danielson et al. (2016) use calcium imaging in mice performing a treadmill task to reveal differences in space-coding dynamics between deep and superficial sublayers of hippocampal CA1, suggesting how the hippocampus might encode both stable and dynamic information simultaneously.
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Affiliation(s)
- Dorothy W U Overington
- Institute of Behavioural Neuroscience, Research Department of Experimental Psychology, Division of Psychology and Language Sciences, University College London, London, WC1H 0AP, UK
| | - Kate J Jeffery
- Institute of Behavioural Neuroscience, Research Department of Experimental Psychology, Division of Psychology and Language Sciences, University College London, London, WC1H 0AP, UK.
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11
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Stuart KE, King AE, Fernandez-Martos CM, Dittmann J, Summers MJ, Vickers JC. Mid-life environmental enrichment increases synaptic density in CA1 in a mouse model of Aβ-associated pathology and positively influences synaptic and cognitive health in healthy ageing. J Comp Neurol 2017; 525:1797-1810. [DOI: 10.1002/cne.24156] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2016] [Revised: 11/09/2016] [Accepted: 11/10/2016] [Indexed: 12/22/2022]
Affiliation(s)
- Kimberley E. Stuart
- Faculty of Health; Wicking Dementia Research and Education Centre, University of Tasmania; Tasmania Australia
| | - Anna E. King
- Faculty of Health; Wicking Dementia Research and Education Centre, University of Tasmania; Tasmania Australia
| | - Carmen M. Fernandez-Martos
- Faculty of Health; Wicking Dementia Research and Education Centre, University of Tasmania; Tasmania Australia
| | - Justin Dittmann
- Faculty of Health; Wicking Dementia Research and Education Centre, University of Tasmania; Tasmania Australia
| | - Mathew J. Summers
- Faculty of Health; Wicking Dementia Research and Education Centre, University of Tasmania; Tasmania Australia
- School of Social Sciences; University of the Sunshine Coast; Sippy Downs Queensland Australia
| | - James C. Vickers
- Faculty of Health; Wicking Dementia Research and Education Centre, University of Tasmania; Tasmania Australia
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12
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Savelli F, Luck JD, Knierim JJ. Framing of grid cells within and beyond navigation boundaries. eLife 2017; 6. [PMID: 28084992 PMCID: PMC5271608 DOI: 10.7554/elife.21354] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 01/11/2017] [Indexed: 12/21/2022] Open
Abstract
Grid cells represent an ideal candidate to investigate the allocentric determinants of the brain's cognitive map. Most studies of grid cells emphasized the roles of geometric boundaries within the navigational range of the animal. Behaviors such as novel route-taking between local environments indicate the presence of additional inputs from remote cues beyond the navigational borders. To investigate these influences, we recorded grid cells as rats explored an open-field platform in a room with salient, remote cues. The platform was rotated or translated relative to the room frame of reference. Although the local, geometric frame of reference often exerted the strongest control over the grids, the remote cues demonstrated a consistent, sometimes dominant, countervailing influence. Thus, grid cells are controlled by both local geometric boundaries and remote spatial cues, consistent with prior studies of hippocampal place cells and providing a rich representational repertoire to support complex navigational (and perhaps mnemonic) processes.
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Affiliation(s)
- Francesco Savelli
- Zanvyl Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, United States
| | - J D Luck
- Zanvyl Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, United States
| | - James J Knierim
- Zanvyl Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, United States.,Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, United States
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13
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Horiuchi TK, Moss CF. Grid cells in 3-D: Reconciling data and models. Hippocampus 2015; 25:1489-500. [PMID: 25913890 DOI: 10.1002/hipo.22469] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/17/2015] [Indexed: 11/11/2022]
Abstract
It is well documented that place cells and grid cells in echolocating bats show properties similar to those described in rodents, and yet, continuous theta-frequency oscillations, proposed to play a central role in grid/place cell formation, are not present in bat recordings. These comparative neurophysiological data have raised many questions about the role of theta-frequency oscillations in spatial memory and navigation. Additionally, spatial navigation in three-dimensions poses new challenges for the representation of space in neural models. Inspired by the literature on space representation in the echolocating bat, we have developed a nonoscillatory model of 3-D grid cell creation that shares many of the features of existing oscillatory-interference models. We discuss the model in the context of current knowledge of 3-D space representation and highlight directions for future research.
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Affiliation(s)
- Timothy K Horiuchi
- Department of Electrical and Computer Engineering, University of Maryland, College Park, Maryland
| | - Cynthia F Moss
- Department of Psychology, Institute for Systems Research, University of Maryland, College Park, Maryland
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14
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Jones BJ, Pest SM, Vargas IM, Glisky EL, Fellous JM. Contextual reminders fail to trigger memory reconsolidation in aged rats and aged humans. Neurobiol Learn Mem 2015; 120:7-15. [PMID: 25698469 DOI: 10.1016/j.nlm.2015.02.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 01/16/2015] [Accepted: 02/02/2015] [Indexed: 11/29/2022]
Abstract
There is strong evidence that hippocampal memory returns to a labile state upon reactivation, initiating a reconsolidation process that restabilizes it and allows for its updating. Normal aging is associated with deficits in episodic memory processes. However, the effects of aging on memory reconsolidation and its neural substrate remain largely unknown, and an animal model is lacking. In this study we investigated the effects of aging on context-dependent reconsolidation using an episodic set-learning task in humans and an analogous set-learning spatial task in rats. In both tasks, young and older subjects learned a set of objects (humans) or feeder locations (rats; Set 1) in Context A on Day 1. On Day 2, a different set (Set 2) was learned in either Context A (Reminder condition) or Context B (No Reminder condition). On Day 3, subjects were instructed (humans) or cued (rats) to recall Set 1. Young rats and humans in the Reminder condition falsely recalled significantly more items from Set 2 than those in the No Reminder condition, suggesting that the reminder context triggered a reactivation of Set 1 on Day 2 and allowed the integration of Set 2 items into Set 1. In both species, older subjects displayed a different pattern of results than young subjects. In aged rats, there was no difference between conditions in the level of falsely recalled Set 2 items (intrusions). Older humans in the No Reminder condition made significantly more intrusions than those in the Reminder condition. Follow-up control experiments in aged rats suggested that intrusions in older animals reflected general interference, independent of context manipulations. We conclude that contextual reminders are not sufficient to trigger memory updating in aged rats or aged humans, unlike in younger individuals. Future studies using this animal model should further our understanding of the role of the hippocampus in memory maintenance and updating during normal aging.
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Affiliation(s)
- Bethany J Jones
- Graduate Interdisciplinary Program in Neuroscience, University of Arizona, Tucson, AZ 85721, United States
| | - Stacey M Pest
- Graduate Interdisciplinary Program in Neuroscience, University of Arizona, Tucson, AZ 85721, United States
| | - Iliana M Vargas
- Department of Psychology, Northwestern University, Evanston, IL 60208, United States
| | - Elizabeth L Glisky
- Department of Psychology, University of Arizona, Tucson, AZ 85721, United States
| | - Jean-Marc Fellous
- Department of Psychology, University of Arizona, Tucson, AZ 85721, United States; Program in Applied Mathematics, University of Arizona, Tucson, AZ 87521-0089, United States.
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15
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Scaplen KM, Gulati AA, Heimer-McGinn VL, Burwell RD. Objects and landmarks: hippocampal place cells respond differently to manipulations of visual cues depending on size, perspective, and experience. Hippocampus 2014; 24:1287-99. [PMID: 25045010 DOI: 10.1002/hipo.22331] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/11/2014] [Indexed: 11/07/2022]
Abstract
Human navigation studies show that landmarks are used for orientation, whereas objects contribute to the contextual representation of an environment. What constitutes a landmark? Classic rodent studies show that hippocampal place fields are controlled by distal, polarizing cues. Place fields, however, are also influenced by local cues. One difficulty in examining mechanisms by which distal and local cues influence the activity of hippocampal cells is that distant cues are necessarily processed visually, whereas local cues are generally multimodal. Here, we compared the effects of 90° rotations under different cue conditions in which cues were restricted to the visual modality. Three two-dimensional visual cue conditions were presented in a square open field: a large vertical cue on one wall, a large floor cue in a corner abutting two walls, and a smaller complex floor cue in a corner adjacent to two walls. We show that rotations of large distal cues, whether on the wall or floor, were equally effective in controlling place fields. Rotations of the smaller floor cues were significantly more likely to result in remapping, whether or not animals were also exposed to the distal polarizing cues. Responses of distal and local cues were affected differently by extended experience. Our data provide evidence that hippocampal place cell responses to visual cues are influenced by perspective, salience of the cue, and prior experience. The hippocampus processes visual cues either as stable landmarks useful for orientation and navigation or as nonstationary objects or features of the local environment available for associative learning or binding items in context.
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Affiliation(s)
- Kristin M Scaplen
- Department of Neuroscience, Brown University, Providence, Rhode Island
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16
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Novelty and anxiolytic drugs dissociate two components of hippocampal theta in behaving rats. J Neurosci 2013; 33:8650-67. [PMID: 23678110 DOI: 10.1523/jneurosci.5040-12.2013] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Hippocampal processing is strongly implicated in both spatial cognition and anxiety and is temporally organized by the theta rhythm. However, there has been little attempt to understand how each type of processing relates to the other in behaving animals, despite their common substrate. In freely moving rats, there is a broadly linear relationship between hippocampal theta frequency and running speed over the normal range of speeds used during foraging. A recent model predicts that spatial-translation-related and arousal/anxiety-related mechanisms of hippocampal theta generation underlie dissociable aspects of the theta frequency-running speed relationship (the slope and intercept, respectively). Here we provide the first confirmatory evidence: environmental novelty decreases slope, whereas anxiolytic drugs reduce intercept. Variation in slope predicted changes in spatial representation by CA1 place cells and novelty-responsive behavior. Variation in intercept predicted anxiety-like behavior. Our findings isolate and doubly dissociate two components of theta generation that operate in parallel in behaving animals and link them to anxiolytic drug action, novelty, and the metric for self-motion.
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17
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Navawongse R, Eichenbaum H. Distinct pathways for rule-based retrieval and spatial mapping of memory representations in hippocampal neurons. J Neurosci 2013; 33:1002-13. [PMID: 23325238 PMCID: PMC3566234 DOI: 10.1523/jneurosci.3891-12.2013] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 10/20/2012] [Accepted: 10/26/2012] [Indexed: 11/21/2022] Open
Abstract
Hippocampal neurons encode events within the context in which they occurred, a fundamental feature of episodic memory. Here we explored the sources of event and context information represented by hippocampal neurons during the retrieval of object associations in rats. Temporary inactivation of the medial prefrontal cortex differentially reduced the selectivity of rule-based object associations represented by hippocampal neuronal firing patterns but did not affect spatial firing patterns. In contrast, inactivation of the medial entorhinal cortex resulted in a pervasive reorganization of hippocampal mappings of spatial context and events. These results suggest distinct and cooperative prefrontal and medial temporal mechanisms in memory representation.
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Affiliation(s)
| | - Howard Eichenbaum
- Center of Memory and Brain, Boston University, Boston, Massachusetts 02115
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18
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Easton A, Douchamps V, Eacott M, Lever C. A specific role for septohippocampal acetylcholine in memory? Neuropsychologia 2012; 50:3156-68. [PMID: 22884957 PMCID: PMC3605586 DOI: 10.1016/j.neuropsychologia.2012.07.022] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2011] [Revised: 05/28/2012] [Accepted: 07/12/2012] [Indexed: 11/30/2022]
Abstract
Acetylcholine has long been implicated in memory, including hippocampal-dependent memory, but the specific role for this neurotransmitter is difficult to identify in human neuropsychology. Here, we review the evidence for a mechanistic model of acetylcholine function within the hippocampus and consider its explanatory power for interpreting effects resulting from both pharmacological anticholinergic manipulations and lesions of the cholinergic input to the hippocampus in animals. We argue that these effects indicate that acetylcholine is necessary for some, but not all, hippocampal-dependent processes. We review recent evidence from lesion, pharmacological and electrophysiological studies to support the view that a primary function of septohippocampal acetylcholine is to reduce interference in the learning process by adaptively timing and separating encoding and retrieval processes. We reinterpret cholinergic-lesion based deficits according to this view and propose that acetylcholine reduces the interference elicited by the movement of salient locations between events.
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Affiliation(s)
- Alexander Easton
- Department of Psychology, University of Durham, Durham, DH1 3LE, UK.
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19
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Place cells, grid cells, attractors, and remapping. Neural Plast 2011; 2011:182602. [PMID: 22135756 PMCID: PMC3216289 DOI: 10.1155/2011/182602] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Accepted: 07/18/2011] [Indexed: 11/22/2022] Open
Abstract
Place and grid cells are thought to use a mixture of external sensory information and internal attractor dynamics to organize their activity. Attractor dynamics may explain both why neurons react coherently following sufficiently large changes to the environment (discrete attractors) and how firing patterns move smoothly from one representation to the next as an animal moves through space (continuous attractors). However, some features of place cell behavior, such as the sometimes independent responsiveness of place cells to environmental change (called “remapping”), seem hard to reconcile with attractor dynamics. This paper suggests that the explanation may be found in an anatomical separation of the two attractor systems coupled with a dynamic contextual modulation of the connection matrix between the two systems, with new learning being back-propagated into the matrix. Such a scheme could explain how place cells sometimes behave coherently and sometimes independently.
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20
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Behavioural deficits associated with maternal immune activation in the rat model of schizophrenia. Behav Brain Res 2011; 225:382-7. [DOI: 10.1016/j.bbr.2011.07.033] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Revised: 07/14/2011] [Accepted: 07/18/2011] [Indexed: 02/06/2023]
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21
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Myers CE, Scharfman HE. Pattern separation in the dentate gyrus: a role for the CA3 backprojection. Hippocampus 2011; 21:1190-215. [PMID: 20683841 PMCID: PMC2976779 DOI: 10.1002/hipo.20828] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/21/2010] [Indexed: 01/31/2023]
Abstract
Many theories of hippocampal function assume that area CA3 of hippocampus is capable of performing rapid pattern storage, as well as pattern completion when a partial version of a familiar pattern is presented, and that the dentate gyrus (DG) is a preprocessor that performs pattern separation, facilitating storage and recall in CA3. The latter assumption derives partly from the anatomical and physiological properties of DG. However, the major output of DG is from a large number of DG granule cells to a smaller number of CA3 pyramidal cells, which potentially negates the pattern separation performed in the DG. Here, we consider a simple CA3 network model, and consider how it might interact with a previously developed computational model of the DG. The resulting "standard" DG-CA3 model performs pattern storage and completion well, given a small set of sparse, randomly derived patterns representing entorhinal input to the DG and CA3. However, under many circumstances, the pattern separation achieved in the DG is not as robust in CA3, resulting in a low storage capacity for CA3, compared to previous mathematical estimates of the storage capacity for an autoassociative network of this size. We also examine an often-overlooked aspect of hippocampal anatomy that might increase functionality in the combined DG-CA3 model. Specifically, axon collaterals of CA3 pyramidal cells project "back" to the DG ("backprojections"), exerting inhibitory effects on granule cells that could potentially ensure that different subpopulations of granule cells are recruited to respond to similar patterns. In the model, addition of such backprojections improves both pattern separation and storage capacity. We also show that the DG-CA3 model with backprojections provides a better fit to empirical data than a model without backprojections. Therefore, we hypothesize that CA3 backprojections might play an important role in hippocampal function.
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Affiliation(s)
- Catherine E Myers
- Department of Psychology, Rutgers University, Newark, New Jersey, USA.
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22
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Jeffery KJ. Theoretical accounts of spatial learning: a neurobiological view (commentary on Pearce, 2009). Q J Exp Psychol (Hove) 2010; 63:1683-99. [PMID: 20204918 PMCID: PMC3160474 DOI: 10.1080/17470210903540771] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Theories of learning have historically taken, as their starting point, the assumption that learning processes have universal applicability. This position has been argued on grounds of parsimony, but has received two significant challenges: first, from the observation that some kinds of learning, such as spatial learning, seem to obey different rules from others, and second, that some kinds of learning take place in processing modules that are separate from each other. These challenges arose in the behavioural literature but have since received considerable support from neurobiological studies, particularly single neuron studies of spatial learning, confirming that there are indeed separable (albeit highly intercommunicating) processing modules in the brain, which may not always interact (within or between themselves) according to classic associative principles. On the basis of these neurobiological data, reviewed here, it is argued that rather than assuming universality of associative rules, it is more parsimonious to assume sets of locally operating rules, each specialized for a particular domain. By this view, although almost all learning is associative in one way or another, the behavioural-level characterization of the rules governing learning may vary depending on which neural modules are involved in a given behaviour. Neurobiological studies, in tandem with behavioural studies, can help reveal the nature of these modules and the local rules by which they interact.
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Affiliation(s)
- Kathryn J Jeffery
- Department of Cognitive, Perceptual and Brain Sciences, Division of Psychology and Language Sciences, Institute of Behavioural Neuroscience, University College London, London, UK.
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23
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Kim J, Lee I. Hippocampus is necessary for spatial discrimination using distal cue-configuration. Hippocampus 2010; 21:609-21. [PMID: 20623761 DOI: 10.1002/hipo.20784] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/12/2010] [Indexed: 11/07/2022]
Abstract
The role of the hippocampus in processing contextual cues has been well recognized. Contextual manipulation often involves transferring animals between different rooms. Because of vague definition of context in such a paradigm, however, it has been difficult to study the role of the hippocampus parametrically in contextual information processing. We designed a novel task in which a different context can be parametrically defined by the spatial configuration of distal cues. In this task, rats were trained to associate two different configurations of distal cue-sets (standard contexts) with different food-well locations at the end of a radial arm. Experiment 1 tested the role of the dorsal hippocampus in retrieving well-learned associations between standard contexts and rewarding food-well locations by comparing rats with neurotoxic lesions in the dorsal hippocampus with controls. We found that the hippocampal-lesioned rats were unable to retrieve the context-place paired associations learned before surgery. To further test the role of the hippocampus in generalizing altered context, in Experiment 2, rats were trained in a task in which modified versions of the standard contexts (ambiguous contexts) were presented, intermixed with the standard contexts. Rats were able to process the ambiguous contexts immediately by using their similarities to the standard contexts, whereas muscimol inactivation of the dorsal hippocampus in the same animals reversibly deprived such capability. The results suggest that rats can effectively associate discrete spatial locations with spatial configuration of distal cues. More important, rats can generalize or orthogonalize modified contextual environments using learned contextual representation of the environment.
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Affiliation(s)
- Jangjin Kim
- Department of Brain and Cognitive Sciences, Seoul National University, Daehak-dong, Gwanak-gu, Korea
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24
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Humphries MD, Prescott TJ. The ventral basal ganglia, a selection mechanism at the crossroads of space, strategy, and reward. Prog Neurobiol 2009; 90:385-417. [PMID: 19941931 DOI: 10.1016/j.pneurobio.2009.11.003] [Citation(s) in RCA: 243] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Revised: 11/12/2009] [Accepted: 11/16/2009] [Indexed: 11/27/2022]
Abstract
The basal ganglia are often conceptualised as three parallel domains that include all the constituent nuclei. The 'ventral domain' appears to be critical for learning flexible behaviours for exploration and foraging, as it is the recipient of converging inputs from amygdala, hippocampal formation and prefrontal cortex, putatively centres for stimulus evaluation, spatial navigation, and planning/contingency, respectively. However, compared to work on the dorsal domains, the rich potential for quantitative theories and models of the ventral domain remains largely untapped, and the purpose of this review is to provide the stimulus for this work. We systematically review the ventral domain's structures and internal organisation, and propose a functional architecture as the basis for computational models. Using a full schematic of the structure of inputs to the ventral striatum (nucleus accumbens core and shell), we argue for the existence of many identifiable processing channels on the basis of unique combinations of afferent inputs. We then identify the potential information represented in these channels by reconciling a broad range of studies from the hippocampal, amygdala and prefrontal cortex literatures with known properties of the ventral striatum from lesion, pharmacological, and electrophysiological studies. Dopamine's key role in learning is reviewed within the three current major computational frameworks; we also show that the shell-based basal ganglia sub-circuits are well placed to generate the phasic burst and dip responses of dopaminergic neurons. We detail dopamine's modulation of ventral basal ganglia's inputs by its actions on pre-synaptic terminals and post-synaptic membranes in the striatum, arguing that the complexity of these effects hint at computational roles for dopamine beyond current ideas. The ventral basal ganglia are revealed as a constellation of multiple functional systems for the learning and selection of flexible behaviours and of behavioural strategies, sharing the common operations of selection-by-disinhibition and of dopaminergic modulation.
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Affiliation(s)
- Mark D Humphries
- Adaptive Behaviour Research Group, Department of Psychology, University of Sheffield, S10 2TN, UK.
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25
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Kim SM, Frank LM. Hippocampal lesions impair rapid learning of a continuous spatial alternation task. PLoS One 2009; 4:e5494. [PMID: 19424438 PMCID: PMC2674562 DOI: 10.1371/journal.pone.0005494] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2009] [Accepted: 04/16/2009] [Indexed: 12/11/2022] Open
Abstract
The hippocampus is essential for the formation of memories for events, but the specific features of hippocampal neural activity that support memory formation are not yet understood. The ideal experiment to explore this issue would be to monitor changes in hippocampal neural coding throughout the entire learning process, as subjects acquire and use new episodic memories to guide behavior. Unfortunately, it is not clear whether established hippocampally-dependent learning paradigms are suitable for this kind of experiment. The goal of this study was to determine whether learning of the W-track continuous alternation task depends on the hippocampal formation. We tested six rats with NMDA lesions of the hippocampal formation and four sham-operated controls. Compared to controls, rats with hippocampal lesions made a significantly higher proportion of errors and took significantly longer to reach learning criterion. The effect of hippocampal lesion was not due to a deficit in locomotion or motivation, because rats with hippocampal lesions ran well on a linear track for food reward. Rats with hippocampal lesions also exhibited a pattern of perseverative errors during early task experience suggestive of an inability to suppress behaviors learned during pretraining on a linear track. Our findings establish the W-track continuous alternation task as a hippocampally-dependent learning paradigm which may be useful for identifying changes in the neural representation of spatial sequences and reward contingencies as rats learn and apply new task rules.
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Affiliation(s)
- Steve M. Kim
- Neuroscience Graduate Program, University of California San Francisco, San Francisco, California, United States of America
| | - Loren M. Frank
- Department of Physiology, University of California San Francisco, San Francisco, California, United States of America
- W.M. Keck Foundation Center for Integrative Neuroscience, University of California San Francisco, San Francisco, California, United States of America
- * E-mail:
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26
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Lever C, Jeewajee A, Burton S, O'Keefe J, Burgess N. Hippocampal theta frequency, novelty, and behavior. Hippocampus 2009. [DOI: 10.1002/hipo.20557] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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27
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Hunsaker MR, Rosenberg JS, Kesner RP. The role of the dentate gyrus, CA3a,b, and CA3c for detecting spatial and environmental novelty. Hippocampus 2008; 18:1064-73. [PMID: 18651615 DOI: 10.1002/hipo.20464] [Citation(s) in RCA: 183] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
It has been suggested that the dentate gyrus (DG) and CA3 cooperate to efficiently process spatial information. The DG has been proposed to be important for fine spatial discrimination, and the CA3 has been proposed to mediate larger scale spatial information processing. To evaluate the roles of the DG and CA3a,b for spatial processing, we developed a task that measures responses to either overall environmental novelty or a response to more subtle changes within the environment. Animals with lesions to the DG showed impaired novelty detection for both environment as well as smaller changes in the environment, whereas animals with lesions to CA3a,b showed no such deficits. A closer look at the lesions suggested that the CA3 lesions included only CA3a and CA3b, but spared CA3c. To test the role of the spared CA3c region, animals with selective lesions to CA3c that spared CA3a,b were run on the same task and showed an intermediate pattern of deficits. These results suggest that the DG is critical for spatial information processing. These data also suggest that CA3 is a heterogeneous structure, with CA3c lesioned animals showing greater spatial processing deficits than CA3a,b lesioned animals. These findings extend our knowledge of hippocampal function and need to be accounted for in future computational models.
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Affiliation(s)
- Michael R Hunsaker
- Department of Psychology, University of Utah, Salt Lake City, Utah 74112, USA
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28
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Temporary inactivation of dorsal hippocampus attenuates explicitly nonspatial, unimodal, contextual fear conditioning. Neurobiol Learn Mem 2008; 90:261-8. [PMID: 18485754 DOI: 10.1016/j.nlm.2008.03.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2008] [Revised: 03/11/2008] [Accepted: 03/13/2008] [Indexed: 11/23/2022]
Abstract
The current study examined the effects of temporary inactivation of the DH on freezing, rearing, ambulating, grooming, and whisking behavior in an explicitly nonspatial contextual fear conditioning paradigm in which olfactory stimuli served as temporally and spatially diffuse contexts. Prior either to training, testing, or both, male Sprague-Dawley rats received bilateral microinfusions of saline or the GABA(A) agonist muscimol into the DH. Results indicate that temporary inactivation of DH produced both anterograde and retrograde deficits in contextually conditioned freezing, while sparing the acquisition and expression of freezing to a discrete auditory or olfactory CS. These data suggest that there is a decidedly nonspatial component to the role of DH in contextual conditioning, and that olfactory contextual conditioning is a fruitful means of further exploring this function.
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29
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Van Cauter T, Poucet B, Save E. Delay-dependent involvement of the rat entorhinal cortex in habituation to a novel environment. Neurobiol Learn Mem 2008; 90:192-9. [PMID: 18440248 DOI: 10.1016/j.nlm.2008.03.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2007] [Revised: 03/04/2008] [Accepted: 03/06/2008] [Indexed: 10/22/2022]
Abstract
Evidence has accumulated that the entorhinal cortex (EC) is involved in memory operations underlying formation of a long-term memory. Because entorhinal-lesioned rats are impaired for long delays in delayed matching and non-matching to sample tasks, it has been proposed that EC contributes to the maintenance of information in short-term memory. In the present study, we asked whether such a time-limited role applies also when learning complex spatial information in a novel environment. We therefore examined the effects of EC lesions on habituation in an object exploration task in which a delay of either 4min or 10min is imposed between successive sessions. EC-lesioned rats exhibited a deficit in habituation at 10min but not 4min delays. Following habituation, reactions to spatial change (object configuration) and non-spatial change (novel object) were also examined. EC-lesioned rats were impaired in detecting the spatial change but were able to detect a non-spatial change, irrespective of the delay. Overall, the results suggest that EC is involved in maintaining a large amount of novel, multidimensional information in short-term memory therefore enabling formation of long-term memory. Switching to a novelty detection mode would then allow the animal to rapidly adapt to environmental changes. In this mode, EC would preferentially process spatial information rather than non-spatial information.
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Affiliation(s)
- Tiffany Van Cauter
- Laboratory of Neurobiology and Cognition, UMR 6155 Aix Marseille Université, CNRS, Pôle 3C, 3 Place Victor Hugo, 13331 Marseille Cedex 3, France
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30
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Self-localization and the entorhinal-hippocampal system. Curr Opin Neurobiol 2008; 17:684-91. [PMID: 18249109 DOI: 10.1016/j.conb.2007.11.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2007] [Revised: 11/24/2007] [Accepted: 11/26/2007] [Indexed: 11/22/2022]
Abstract
Self-localization requires that information from several sensory modalities and knowledge domains be integrated in order to identify an environment and determine current location and heading. This integration occurs by the convergence of highly processed sensory information onto neural systems in entorhinal cortex and hippocampus. Entorhinal neurons combine angular and linear self-motion information to generate an oriented metric signal that is then 'attached' to each environment using information about landmarks and context. Neurons in hippocampus use this signal to determine the animal's unique position within a particular environment. Elucidating this process illuminates not only spatial processing but also, more generally, how the brain builds knowledge representations from inputs carrying heterogeneous sensory and semantic content.
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31
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Abstract
The hippocampal place cells are a highly multimodal class of neurons, receiving information from many different sensory sources to correctly localize their firing to restricted regions of an environment. Evidence suggests that the sensory information is processed upstream of the hippocampus, to extract both angular and linear metric information, and also contextual information. These various kinds of information need to be integrated for coherent firing fields to be generated, and the present article reviews recent evidence concerning how this occurs. It is concluded that there is a functional dissociation of the cortical inputs, with one class of incoming information comprising purely metric information concerning distance and orientation, probably routed via the grid cells and head direction cells. The other class of information is much more heterogeneous and serves, at least in part, to contextualize the spatial inputs so as to provide a unique representation of the place the animal is in. Evidence from remapping studies suggests that the metric and contextual inputs interact upstream of the place cells, perhaps in entorhinal cortex. A full understanding of the generation of the hippocampal place representation will require elucidation of the representational functions of the afferent cortical areas.
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Affiliation(s)
- Kathryn J Jeffery
- Department of Psychology, Institute of Behavioural Neuroscience, University College London, 26 Bedford Way, London, United Kingdom.
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32
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Siegel JJ, Neunuebel JP, Knierim JJ. Dominance of the proximal coordinate frame in determining the locations of hippocampal place cell activity during navigation. J Neurophysiol 2007; 99:60-76. [PMID: 17959742 DOI: 10.1152/jn.00731.2007] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The place-specific activity of hippocampal cells provides downstream structures with information regarding an animal's position within an environment and, perhaps, the location of goals within that environment. In rodents, recent research has suggested that distal cues primarily set the orientation of the spatial representation, whereas the boundaries of the behavioral apparatus determine the locations of place activity. The current study was designed to address possible biases in some previous research that may have minimized the likelihood of observing place activity bound to distal cues. Hippocampal single-unit activity was recorded from six freely moving rats as they were trained to perform a tone-initiated place-preference task on an open-field platform. To investigate whether place activity was bound to the room- or platform-based coordinate frame (or both), the platform was translated within the room at an "early" and at a "late" phase of task acquisition (Shift 1 and Shift 2). At both time points, CA1 and CA3 place cells demonstrated room-associated and/or platform-associated activity, or remapped in response to the platform shift. Shift 1 revealed place activity that reflected an interaction between a dominant platform-based (proximal) coordinate frame and a weaker room-based (distal) frame because many CA1 and CA3 place fields shifted to a location intermediate to the two reference frames. Shift 2 resulted in place activity that became more strongly bound to either the platform- or room-based coordinate frame, suggesting the emergence of two independent spatial frames of reference (with many more cells participating in platform-based than in room-based representations).
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Affiliation(s)
- Jennifer J Siegel
- Department of Neurobiology and Anatomy, University of Texas Medical School at Houston, Houston, Texas, USA.
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